Communication systems for transmitting data point to point are well known, such as conventional telex systems and data base access systems. In addition, of course, telephone systems are well known two-way conversational communication media with the disadvantage being that a telephone system does not provide any hard copy nor does it allow you to, on the same device, obtain supplementary data while carrying on the conversation. Such supplementary data may be particularly important if the purpose of the conversation is commodity dealing such as in the money market. With respect to the telex communication, apart from its associated rate of speed, it does not enable you to readily carry on two different two-way telex communications alternatively so that you can carry on "telex conversations" with two different subscribers at substantially the same time. Moreover, neither the telex communication systems nor telephone communication systems provide a listing of incoming callers prior to acceptance of the message by the recipient. With respect to two-way data-base access systems, such prior art systems do not in reality provide a real time conversational communication in that they merely provide for remote storage of information which may subsequently be retrieved upon request by a subscriber or, in certain instances, can be provided to the subscriber if he is accessing the particular storage location to which the data is being provided. However, this is still not a real-time conversational type of video communication system in which a pair of subscribers or users can interact in real time in a conversational mode. With respect to prior art telephone and data-base access systems, a prior art system merging these two technologies is known as the Delphi system which is a telephone message management system in which speech messages may be pre-recorded and stored in a data base for subsequent automatic transmission to incoming callers and in which incoming messages may be stored for subsequent later transmission to prescribed recipients. However, this system is not a true conversational video communication system nor does it enable a particular user to carry on multiple conversations substantially simultaneously. Thus, there are no satisfactory prior art systems known to applicants which are capable of providing interactive conversational type of video data communications between pairs of users or subscribers nor such systems which enable multiple conversations to be carried out by a given user or subscriber in real-time and in association with data-base retrieval of supplementary data. These disadvantages of the prior art are overcome by the systems disclosed in the aforementioned copending U.S. patent applications. However the systems disclosed therein do not adequately provide for quick and secure confirmation of a transaction such as through use of a DEAL KEY, and moreover, require access to the SUBSCRIBER FILE in the host computer to retrieve the CONTACT LIST or the INHIBIT LIST before processing could continue of a CONTACT REQUEST. This could impose an unacceptably heavy overload on the host computer and affect the efficiency of the system. In the system of the present invention these disadvantages have been overcome.